Merge: Intro of nitrestful a RESTful API generator

This tool generate a Nit module which implements `Action::answer` to redirect request to a static Nit method. It checks the presence of args, their types, deserialize objects as needed and calls the target method.

Missing arguments or arguments with errors (wrong type, failed deserialization, etc.) are replaced by `null` when the corresponding parameter is `nullable`. If the parameter is non-nullable, or if there is any other error, the generated code calls `super` from `answer` for the user code to handle exceptions and errors.

With the `restful` annotation we can write a normal method with static types such as: (from the example)
~~~
# User code
class MyAction
	super RestfulAction

	# Method answering requests like `foo?s=some_string&i=42&b=true`
	fun foo(s: String, i: Int, b: Bool): HttpResponse is restful do
		var resp = new HttpResponse(200)
		resp.body = "foo {s} {i} {b}"
		return resp
	end
...
~~~

And nitrestful will generate for use the wrapper extracting the args from the request and call the method `foo`:
~~~
# Generated code by `nitrestful`
redef class MyAction
	redef fun answer(request, truncated_uri)
	do
		var verbs = truncated_uri.split("/")
		if verbs.not_empty and verbs.first.is_empty then verbs.shift
		if verbs.length != 1 then return super
		var verb = verbs.first

		if verb == "foo" then
			var in_s = request.string_arg("s")
			var out_s = in_s

			var in_i = request.string_arg("i")
			var out_i = deserialize_arg(in_i)

			var in_b = request.string_arg("b")
			var out_b = deserialize_arg(in_b)

			if not out_s isa String or not out_i isa Int or not out_b isa Bool then
				return super
			end
			return foo(out_s, out_i, out_b)
		end
		return super
	end
end
~~~

This is an early version of this tool. More work is needed to test different types, different usages, error management, and improve the docs and examples.

close #1852

Pull-Request: #1863
Reviewed-by: Jean Privat <jean@pryen.org>
Reviewed-by: Romain Chanoir <romain.chanoir@viacesi.fr>
Reviewed-by: Jean-Philippe Caissy <jpcaissy@piji.ca>

contrib/jwrapper/Makefile

@@ -12,7 +12,7 @@ src/javap_test_parser.nit: ../nitcc/src/nitcc grammar/javap.sablecc
 	mv javap* gen/
 
 src/serial.nit: $(shell ../../bin/nitls -M src/jwrapper.nit)
-	../../bin/nitserial -o src/serial.nit -d package src/jwrapper.nit
+	../../bin/nitserial -o src/serial.nit src/jwrapper.nit
 
 bin/jwrapper: src/javap_test_parser.nit src/serial.nit $(shell ../../bin/nitls -M src/jwrapper.nit) ../../bin/nitc
 	mkdir -p bin

contrib/jwrapper/src/model.nit

@@ -157,7 +157,7 @@ class NitType
 	var identifier: String
 
 	# If this NitType was found in `lib/android`, contains the module name to import
-	var mod: nullable NitModule
+	var mod: nullable NitModuleRef
 
 	# Is this type known, wrapped and available in Nit?
 	var is_known: Bool = true
@@ -183,7 +183,7 @@ class JavaClass
 	var constructors = new Array[JavaConstructor]
 
 	# Importations from this class
-	var imports = new HashSet[NitModule]
+	var imports = new HashSet[NitModuleRef]
 
 	# Interfaces implemented by this class
 	var implements = new HashSet[JavaType]
@@ -482,15 +482,15 @@ class JavaConstructor
 end
 
 # A Nit module, use to import the referenced extern classes
-class NitModule
+class NitModuleRef
 	# Relative path to the module
 	var path: String
 
 	# Name of the module
 	var name: String is lazy do return path.basename(".nit")
 
 	redef fun to_s do return self.name
-	redef fun ==(other) do return other isa NitModule and self.path == other.path
+	redef fun ==(other) do return other isa NitModuleRef and self.path == other.path
 	redef fun hash do return self.path.hash
 end
 
@@ -501,7 +501,7 @@ redef class Sys
 	# * The value is the corresponding `NitType`.
 	var find_extern_class: DefaultMap[String, nullable NitType] is lazy do
 		var map = new DefaultMap[String, nullable NitType](null)
-		var modules = new HashMap[String, NitModule]
+		var modules = new HashMap[String, NitModuleRef]
 
 		var lib_paths = opt_libs.value
 		if lib_paths == null then lib_paths = new Array[String]
@@ -543,7 +543,7 @@ redef class Sys
 
 				var mod = modules.get_or_null(path)
 				if mod == null then
-					mod = new NitModule(path)
+					mod = new NitModuleRef(path)
 					modules[path] = mod
 				end
 

lib/gen_nit.nit

@@ -15,6 +15,8 @@
 # Support to generate and otherwise manipulate Nit code
 module gen_nit
 
+import template
+
 redef class Sys
 	# Reserved keywords in the Nit language
 	var keywords: Set[String] is lazy do return new HashSet[String].from([
@@ -39,3 +41,37 @@ redef class Sys
 	var methods_in_pointer: Array[String] is lazy do return methods_in_object + [
 		"free"]
 end
+
+# Template of a Nit module to generate Nit code
+class NitModule
+	super Template
+
+	# Header on top of the module, usually the documentation
+	var header: nullable Writable = null is writable
+
+	# The module's name
+	var name: Writable is writable
+
+	# Imports from this module
+	var imports = new Array[Writable]
+
+	# Main content of this module
+	var content = new Array[Writable]
+
+	redef fun rendering
+	do
+		var header = header
+		if header != null then add header
+
+		var name = name
+		add "module {name}\n\n"
+
+		for i in imports do add "import {i}\n"
+		add "\n"
+
+		for l in content do
+			add l
+			add "\n"
+		end
+	end
+end

lib/nitcorn/examples/.gitignore

@@ -0,0 +1 @@
+src/restful_annot_gen.nit

lib/nitcorn/examples/Makefile

@@ -1,7 +1,15 @@
-all:
+all: bin/restful_annot
 	mkdir -p bin/
 	../../../bin/nitc --dir bin src/nitcorn_hello_world.nit src/simple_file_server.nit
 
 xymus.net:
 	mkdir -p bin/
 	../../../bin/nitc --dir bin/ src/xymus_net.nit
+
+pre-build: src/restful_annot_gen.nit
+src/restful_annot_gen.nit:
+	../../../bin/nitrestful -o $@ src/restful_annot.nit
+
+bin/restful_annot: src/restful_annot_gen.nit
+	mkdir -p bin/
+	../../../bin/nitc -o $@ src/restful_annot_gen.nit

lib/nitcorn/examples/src/restful_annot.nit

@@ -0,0 +1,47 @@
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import nitcorn::restful
+
+class MyAction
+	super RestfulAction
+
+	# Method answering requests like `foo?s=some_string&i=42&b=true`
+	fun foo(s: String, i: Int, b: Bool): HttpResponse
+	is restful do
+		var resp = new HttpResponse(200)
+		resp.body = "foo {s} {i} {b}"
+		return resp
+	end
+
+	# Method answering requests like `bar?s=these_arguments_are_optional`
+	fun bar(s: nullable String, i: nullable Int, b: nullable Bool): HttpResponse
+	is restful do
+		var resp = new HttpResponse(200)
+		resp.body = "bar {s or else "null"} {i or else "null"} {b or else "null"}"
+		return resp
+	end
+end
+
+var vh = new VirtualHost("localhost:8080")
+
+# Serve everything with our restful action
+vh.routes.add new Route(null, new MyAction)
+
+# Avoid executing when running tests
+if "NIT_TESTING".environ == "true" then exit 0
+
+var factory = new HttpFactory.and_libevent
+factory.config.virtual_hosts.add vh
+factory.run

lib/nitcorn/restful.nit

@@ -0,0 +1,45 @@
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Support module for the `nitrestful` tool and the `restful` annotation
+module restful is new_annotation(restful)
+
+import nitcorn
+import json::serialization
+
+# Action with `restful` methods
+class RestfulAction
+	super Action
+
+	redef fun answer(request, truncated_uri) do return new HttpResponse(400)
+
+	# Service to deserialize arguments from JSON
+	#
+	# Accepts `nullable String` for convenience, but returns `null` when `val == null`.
+	#
+	# This method is called by the code generated by `nitrestful`.
+	# It can be specialized to customize its behavior.
+	protected fun deserialize_arg(val: nullable String): nullable Object
+	do
+		if val == null then return null
+
+		var deserializer = new JsonDeserializer(val)
+		if deserializer.errors.not_empty then
+			print_error deserializer.errors.join("\n")
+			return null
+		end
+
+		return deserializer.deserialize
+	end
+end

share/man/nitrestful.md

@@ -0,0 +1,19 @@
+# NAME
+
+nitrestful - generates boilerplate code to relay RESTful request to static Nit methods
+
+# SYNOPSIS
+
+nitrestful [*options*]... FILE
+
+# OPTIONS
+
+### `-o`, `--output`
+Output file (can also be 'stdout').
+
+### `--dir`
+Output directory.
+
+# SEE ALSO
+
+The Nit language documentation and the source code of its tools and libraries may be downloaded from <http://nitlanguage.org>

src/Makefile

@@ -16,7 +16,7 @@
 
 NITCOPT=--semi-global
 OLDNITCOPT=--semi-global
-OBJS=nitc nitpick nit nitdoc nitls nitunit nitpretty nitmetrics nitx nitlight nitdbg_client nitserial
+OBJS=nitc nitpick nit nitdoc nitls nitunit nitpretty nitmetrics nitx nitlight nitdbg_client nitserial nitrestful
 SRCS=$(patsubst %,%.nit,$(OBJS))
 BINS=$(patsubst %,../bin/%,$(OBJS))
 

src/frontend/serialization_phase.nit

@@ -56,7 +56,6 @@ redef class ADefinition
 	end
 end
 
-# TODO add annotations on attributes (volatile, sensitive or do_not_serialize?)
 private class SerializationPhasePreModel
 	super Phase